This invention relates to the alignment of optical fibers to optoelectronic devices and, more particularly, to the alignment of arrays of fibers to arrays of devices.
Workers worldwide are giving considerable attention to the problem of monolithically integrating various types of optoelectronic devices on a single substrate. The integration of linear arrays of photodetectors (e.g., photodiodes) and linear arrays of light emitters (e.g., laser diodes or LEDs) represents one area of particular interest. Such integrated device arrays would be useful, for example, in parallel data-bus transmission and in high fiber density applications. In addition, new fiber-optic system architectures are made possible by the use of such arrays. For example, the spatial multiplexing envisioned by a video switch having hundreds, if not thousands, of input/outputs would be too bulky if constructed of discrete devices but considerably more compact and practical if made from monolithic arrays.
However, a continuing problem encountered in the packaging of optoelectronic devices for use in fiber-optic lightwave communication sytems is the alignment of optical fibers to the optically active region of these devices. Alignment tolerances are typically on the order of 10-20 .mu.m for multimode systems and are considerably smaller for single mode systems. Most alignment schemes are performed actively; i.e., a photogenerated electrical response is maximized as a function of the position of the fiber with respect to the device's active region. Although this method can in principle be automated, it is a complex procedure. In present manufacturing processes this alignment scheme requires a considerable amount of time by a skilled technician. The problems with alignment are exacerbated with arrays of devices because of the increased number of fibers which must be simultaneously aligned to the devices.